1. Field
The invention relates to throttle body assemblies for internal combustion engines, and in particular, the injection molding of a shaft and blade component in situ within the throttle body housing.
2. Background Art
A throttle is the mechanism that constricts or obstructs the flow of a fluid. An engine's power may be increased or decreased by the restriction of inlet gases by the use of a throttle. In a fuel-injected engine, the throttle is typically placed on the entrance of the intake manifold, or housed in a throttle body. In a carbureted engine, it is found in the carburetor.
A fuel-injected engine's throttle is typically a butterfly valve located within the interior passage of a throttle body assembly. When the blade of the butterfly valve is wide open (in-line with fluid flow), the engine may run at full power. When the blade of the butterfly valve is partially closed (at an angle to the fluid flow), the engine's power is decreased.
Butterfly valves within throttle body assemblies may be controlled by an operator using a pedal or lever with a direct mechanical linkage, or with an Engine Control Unit (ECU). ECUs receive information from sensors (or the operator), process the information, and in turn control the position of the butterfly valve. Often the position of the butterfly valve, as controlled by an ECU, is based on the desired engine outputs as programmed into the ECU. The ECU sends a signal to rotate the blade of the butterfly valve inside the throttle body, opening the throttle passage to allow more air into the intake manifold increasing the engine's power.
Examples of throttle body assemblies and ECUs used with internal combustion engines may be found in U.S. Pat. Nos. 6,804,997 and 6,955,081 to Schwulst, and U.S. Pat. No. 7,225,793 to Schwulst et al., all of which are hereby incorporated by reference in their entirety.
Traditionally throttle body assemblies have been made of metal with a multi-component pin and blade sub-assembly assembled into the interior passage of the throttle body housing. Some improvements to this traditional design have included injection molded throttle body housings with blades injection molded in the throttle body housing around, or connected to, an inserted pin (or pins) to support and rotate the blade. These throttle body assemblies require additional complexity of bushings and seals to manage the support of the pin(s) and allow rotation of the blade.
The following references were considered in conjunction with preparing this application: U.S. Pat. No. 7,846,364 to Arai et al., U.S. Pat. No. 7,790,083 to Lorenz et al., U.S. Pat. No. 7,328,507 to Arai et al., U.S. Pat. No. 7,107,679 to Arai et al., U.S. Pat. No. 7,107,678 to Arai et al., U.S. Pat. No. 7,089,663 to Arai et al., U.S. Pat. No. 7,069,902 to Arai et al., U.S. Pat. No. 5,421,718 to Karlsson et al., U.S. Pat. No. 5,304,336 to Karlsson et al., and U.S. P.G. Pub. No. 2010/0090148 to Deiss et al.